containerd的客户端工具ctr命令

containerd的客户端工具ctr命令

类似docker为docker-shim容器运行时的客户端工具，ctr 是 containerd 的客户端工具，安装containerd作为容器运行时后，会自动安装ctr。

root@master1:~# ctr -v
ctr github.com/containerd/containerd 1.7.12

1. 帮助文档

ctr帮助文档

root@master1:~# ctr --help

containerd CLI

USAGE:
   ctr [global options] command [command options] [arguments...]

VERSION:
   1.7.12

DESCRIPTION:

ctr is an unsupported debug and administrative client for interacting
with the containerd daemon. Because it is unsupported, the commands,
options, and operations are not guaranteed to be backward compatible or
stable from release to release of the containerd project.

COMMANDS:
   plugins, plugin            Provides information about containerd plugins
   version                    Print the client and server versions
   containers, c, container   Manage containers
   content                    Manage content
   events, event              Display containerd events
   images, image, i           Manage images
   leases                     Manage leases
   namespaces, namespace, ns  Manage namespaces
   pprof                      Provide golang pprof outputs for containerd
   run                        Run a container
   snapshots, snapshot        Manage snapshots
   tasks, t, task             Manage tasks
   install                    Install a new package
   oci                        OCI tools
   sandboxes, sandbox, sb, s  Manage sandboxes
   info                       Print the server info
   deprecations
   shim                       Interact with a shim directly
   help, h                    Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --debug                      Enable debug output in logs
   --address value, -a value    Address for containerd's GRPC server (default: "/run/containerd/containerd.sock") [$CONTAINERD_ADDRESS]
   --timeout value              Total timeout for ctr commands (default: 0s)
   --connect-timeout value      Timeout for connecting to containerd (default: 0s)
   --namespace value, -n value  Namespace to use with commands (default: "default") [$CONTAINERD_NAMESPACE]
   --help, -h                   show help
   --version, -v                print the version

注意：

ctr与docker较大的一个区别再用ctr有命名空间的概念，下面的命令执行时候如果没加-n参数，表示default命名空间。当containerd结合k8s使用时，相关镜像一般存放到k8s.io，相关操作需要加-n k8s.io，且将参数放到最前面。

子命令帮助文档，通过ctr+子命令查看帮助信息：

root@master1:~# ctr plugins
NAME:
   ctr plugins - Provides information about containerd plugins

USAGE:
   ctr plugins command [command options] [arguments...]

COMMANDS:
   list, ls  Lists containerd plugins

OPTIONS:
   --help, -h  show help

2. 镜像操作

帮助信息：

root@master1:~# ctr images
NAME:
   ctr images - Manage images

USAGE:
   ctr images command [command options] [arguments...]

COMMANDS:
   check                    Check existing images to ensure all content is available locally
   export                   Export images
   import                   Import images
   list, ls                 List images known to containerd
   mount                    Mount an image to a target path
   unmount                  Unmount the image from the target
   pull                     Pull an image from a remote
   push                     Push an image to a remote
   prune                    Remove unused images
   delete, del, remove, rm  Remove one or more images by reference
   tag                      Tag an image
   label                    Set and clear labels for an image
   convert                  Convert an image
   usage                    Display usage of snapshots for a given image ref

OPTIONS:
   --help, -h  show help

拉取镜像:

# 帮助信息
[root@k8s ~]# ctr images pull --help
NAME:
   ctr images pull - pull an image from a remote

USAGE:
   ctr images pull [command options] [flags] <ref>

DESCRIPTION:
   Fetch and prepare an image for use in containerd.

After pulling an image, it should be ready to use the same reference in a run
command. As part of this process, we do the following:

1. Fetch all resources into containerd.
2. Prepare the snapshot filesystem with the pulled resources.
3. Register metadata for the image.


OPTIONS:
   --skip-verify, -k                 skip SSL certificate validation
   --plain-http                      allow connections using plain HTTP
   --user value, -u value            user[:password